Enum field validation fallback

[dwbelliston]

Hey!

What is the approach to provide a default value if a field validation fails?

Example:

FieldName: FieldEnum

If an existing record has a value outside this enum, id like to set it to a default on the enum.

Is this possible?

[PrettyWood]

Hi @dwbelliston
IMO the best way is to overwrite _missing_ in your Enum like this

from enum import Enum, auto

from pydantic import BaseModel


class Fruit(Enum):
    APPLE = auto()
    PEAR = auto()

    @classmethod
    def _missing_(cls, value):
        return cls.APPLE


class Model(BaseModel):
    fruit: Fruit

print(Model(fruit=Fruit.APPLE).fruit)  # Fruit.APPLE
print(Model(fruit=Fruit.PEAR).fruit)  # Fruit.PEAR
print(Model(fruit='invalid').fruit)  # Fruit.APPLE

Hope it helps!

[dwbelliston]

oh awesome - thank you! :) that helps a lot